1. Field of the Invention
The present invention relates to a liquid jet recording head, and a method for manufacturing such liquid jet recording head, and a liquid jet recording apparatus using such liquid jet recording head.
2. Related Background Art
Generally, a liquid jet recording head includes fine recording liquid discharge openings, liquid passages communicating with the respective discharge openings, and energy generating elements arranged in correspondence to the respective liquid passages and each adapted to generate energy utilized to discharge the recording liquid from the corresponding discharge opening. In the past, as a technique for manufacturing such liquid jet recording head, it was known to prepare a plate made of glass, metal or the like, to form fine or narrow grooves in the plate by cutting or etching, and then to laminate the plate so formed with another suitable plate to define liquid passages therebetween.
However, in the liquid jet recording head manufactured by the above-mentioned conventional technique, it was difficult to obtain liquid passages having uniform liquid resistance because of the rough surface of the inner wall of the liquid passage worked or finished by the cutting or the distortion of the liquid passage due to the difference in the etching rate, thus causing irregularity in the recording liquid discharge feature of the liquid jet recording head. Further, when the head was manufactured by using the etching technique, a relatively large number of manufacturing steps were required, thus increasing the manufacturing cost of the head. In addition, as a problem common to the conventional techniques, when the plate in which the grooves for forming the liquid passages are formed was laminated with another plate (substrate) on which energy generating elements, such as piezo-electric elements or electrical/thermal converters for generating energy utilized to discharge the recording liquid, are disposed, it was difficult to register these plates with each other, thus reducing the productivity.
In order to eliminate the above-mentioned drawbacks, Japanese Patent Laid-open No. 57-43876 (corresponding to U.S. Pat. No. 4,417,251) discloses a method for manufacturing a liquid jet recording head as schematically shown in FIG. 1. More particularly, a photosensitive resin layer 16 (for example, made of LAMINAR (manufactured by DYNA CHEMICAL CO.), SR-1000G-50 (manufactured by HITACHI CHEMICAL CO.), SR-1000N (manufactured by HITACHI CHEMICAL CO.) or the like which are negative photosensitive resin films) is coated on a substrate plate 1 (FIG. 1A) on which energy generating elements 7 are formed, and then the plate is subjected to predetermined pattern exposure to form the cured areas on the photosensitive resin layer 16. Thereafter, by removing the non-cured resin material from the photosensitive resin layer, grooves for forming liquid paths including liquid passages 14 communicating with discharge openings 13 and a common liquid chamber 15 are obtained in the plate (FIG. 1B). Then, a lid 4 having a recess 9 communicating with liquid supply openings 6 is securely attached to the plate 1 with an adhesive 3, thus obtaining a liquid jet recording head (FIG. 1C). According to this manufacturing method, since the liquid paths are formed by the photolithography technique, the liquid paths can be formed uniformly and the productivity can be improved.
However, this method has the following drawbacks:
(a) It is feared that dirt and the like will enter into the liquid paths during the manufacture of the head after the formation of the liquid paths and before the lamination of the two plates, thus reducing the yield rate; PA1 (b) Since adhesive is used to laminate the two plates, it is feared that the adhesive will enter into the liquid paths; and PA1 (c) The more the number and the density of the discharge openings are increased, the more the above problems (a) and (b) are noticeable.
In order to solve the above problems, Japanese Patent Laid-open No. 62-253457 (corresponding to U.S. Pat. No. 5,030,317) discloses a method as shown schematically in FIG. 2. More particularly, a solid layer 8 is disposed on a substrate plate 1 at a position where liquid paths are to be formed (FIG. 2A), and a layer made of material curable by active energy rays, as a path wall forming material 2, is laminated on the solid layer 8 (FIG. 2B) and then a lid 4 having a recess 9 communicating with liquid supply openings 6 is laminated on the material 2 (FIG. 2C). Thereafter, a photo-mask 12 is disposed, and then the active energy rays (shown by the arrows 11) are illuminated to cure a part of the material 2 (corresponding to a portion where the common liquid chamber to be formed) (FIG. 2D). Then, by supplying a solid removing liquid from the liquid supply opening 6 (FIG. 2E), the non-cured solid layer 8 is removed, thus forming the liquid passages communicating with the discharge openings 13 (FIG. 2F).
However, in such a method, particularly when the lid 4 is laminated, the following problems arise:
(1) When the lid 4 is laminated, it is necessary to apply a pressure to the lid 4 to an extent that the solid layer 8 is not destroyed by the lid. If the pressure is too high, a thickness of a top wall (ceiling wall) portion of the path wall forming material 2 is reduced. Consequently, it is feared that the top wall portion is broken or lowered into the liquid paths during the subsequent processes; and
(2) When the lid 4 is laminated, if the above-mentioned pressure is too low, the lid 4 is not perfectly attached to the path wall forming material 2, with the result that the lid 4 will be curved to make the thickness of the path wall forming material 2 uneven. Consequently, it is feared that the shrinking stress of the thicker portion of the path wall forming material 2 is increased during the curing thereof to cause the curvature of the head itself and/or the peeling of the path wall forming material 2. Further, at the thinner portion of the path wall forming material 2, it is feared that there arises a problem similar to the above problem (1).
Although the above-mentioned problems are not so serious and can be coped with if the number of the discharge openings is relatively small and the density of the discharge openings is not so high, the more the number and density of the discharge openings are increased, the more the problems are noticeable. Particularly, in a liquid jet recording head of a so-called full-line type wherein a great number (for example, several thousands) of discharge openings are arranged across the whole recording area with high density and a great number of corresponding energy generating elements are arranged on the substrate plate with high density, the above problems are very serious.